Rail Tunnel Clearance Surveys Summary:

Severn Partnership have a combination or ‘ClearRoute’ SCO Laser sweeps, Terrestrial laser scanners and Kinematic (rapid push through) track devices to quickly survey tunnels for clearance, sections and portals. Also, for bridgeguard, maintenance or track alignment design alterations.

With tunnel gauging surveys, many of the deliverables will be identical to other standard rail surveys:

• Marked chainage
• Track survey and topographical detail
• OHLE heights and stagger
• Clearance gauging profiles (clearRoute sco files)
• Survey control points
• TMG Spigot control

However, tunnel surveys present their own specific problems and demand a specialist knowledge to arrive at valid solutions. We have extensive knowledge of working in tunnel environments and know how to coordinate survey stations effectively underground, maintain survey control against tamping, survey multiple ‘ClearRoute’ sections, detail changes in construction and arrange the appropriate site access.

Tunnel surveys are also well suited to laser scanning. For example, in an irregular rock cutting, engineers may not know specifically where the main clearance problem areas are. Therefore the survey of cross sections would be an iterative affair, involving costly site re-visits. With 3D Laser scanning, additional cross sections can be requested once the initial field work is completed: even requesting sections every half metre or less if required.

We acquired the Amberg GRP system FX for trolley based helical scanning; giving us the ability to gauge over 1km per hour through tunnels. This system can also collect high accuracy track geometry and absolute position data and allow quality checks for:

• Tunnel modifications
• Tunnel clearance and profile checks
• Tunnel monitoring & comparisons
• Inventory surveys and assessment databases

Examples of Relevant Experience Include:

• Severn Tunnel traverse and drainage survey
• Irregular bare rock tunnel for clearance surveys (Blaenau Ffestiniog)
• Thameslink tunnels
• Box Tunnel traverse, topographic survey, ClearRoute clearance SCO sections (GW Electrification project)
• Sodbury Tunnel topographic survey, ClearRoute clearance SCO profiles
• Birmingham bridgeguard tunnel surveys
• Monitoring movement at Manton Tunnel and Birmingham New Street

For more information please email us at info@severnpartnership.com or speak to us on 01952 676 775.